Field
The present invention relates to a rechargeable battery in which a cap plate is coupled and welded to an opening of a case.
Description of the Related Art
A rechargeable battery can repeatedly perform charge and discharge, unlike a primary battery. A rechargeable battery of a small capacity is used for a small portable electronic device like a mobile phone or a laptop computer and a camcorder, and a rechargeable battery of a large capacity is used as a power source for driving a motor of a hybrid vehicle and an electric vehicle
For example, a rechargeable battery includes an electrode assembly that performs a charge and discharge operation, a case that houses the electrode assembly and an electrolyte solution, a cap plate that is coupled to an opening of the case, and an electrode terminal that is installed at the cap plate to be electrically connected to the electrode assembly.
The case has a step corresponding to the cap plate in the opening. When placing and welding the cap plate in the opening of the case, the step may prevent the cap plate from falling inside of the case. However, by adding a production process of the case, the step increases production cost.
Due to the step, the opening of the case is formed with a thin thickness. Therefore, a crack may occur in the case, and when a crush or drop occurs, the step portion may be broken by physical impact. That is, in a welding process of the case and the cap plate, a defect rate may increase.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.